Hiccups while pinging

I noticed some slight delays using my wireless connection. Digging into it a little, I noticed the following...

When pinging my WRT54G from the laptop over the air, the ping times are approx. 1ms for the majority of the time, although there seems to be an underlying regular pattern of packets with ping times nearing a second. If I use my 802.11b client adapter instead of the 802.11g, it works as better with almost all packets having similar 1ms response times. I'm working in a fairly clean RF environment with little interference, line-of-sight to the ap, and a distance of 15 feet. The signal level never varies from 100%.